Dodecyl Dimethyl Ammonium Research Articles

Surfactant-mediated enhancement of liquid permeability in scots pine wood

Scots pine (Pinus sylvestris L.) is a widely-used wood species in construction and exterior applications. However, inherently low liquid permeability of wood presents substantial challenges to processing efficiency. In order to improve the liquid permeability in Scots pine, the effect of two different surfactants including dodecyl dimethyl ammonium chloride (DDAC) and primary alcobol ethoxylate (JFC-U) were investigated in this study. The mechanism was unveiled by microscopic observation, chemical analysis of extractive composition, and molecular dynamics (MD) simulations. The results demonstrated that both surfactants increased the liquid absorption in Scots pine by 14.7–46.3 % within 0.5 h. This effect was mainly attributed to the surfactants' capability to enhance surface wetting and dissolve extractives deposited on pit membrane in Scots pine wood. DDAC outperformed JFC-U in dissolving extractives. The MD simulations between DDAC and stearic acid (a representative extractive) illustrated that DDAC could envelope stearic acid molecules and form micellar structures through the strong intermolecular forces between them. These findings provide valuable insights into the effect and mechanisms by which surfactants enhance liquid permeability in extractive-rich wood, therefore, to support the development of efficient wood treatment technologies.

In Vitro Metabolism of Quaternary Ammonium Compounds and Confirmation in Human Urine by Liquid Chromatography Ion-Mobility High-Resolution Mass Spectrometry.

Quaternary ammonium compounds (QACs) are high-production chemicals used as cleaning and disinfecting agents. Due to their ubiquitous presence in the environment and several toxic effects described, human exposure to these chemicals gained increasing attention in recent years. However, very limited data on the biotransformation of QACs is available, hampering exposure assessment. In this study, three QACs (dimethyl dodecyl ammonium, C10-DDAC; benzyldimethyl dodecylammonium, C12-BAC; cetyltrimethylammonium, C16-ATMAC) commonly detected in indoor microenvironments were incubated with human liver microsomes and cytosol (HLM/HLC) simulating Phase I and II metabolism. Thirty-one Phase I metabolites were annotated originating from 19 biotransformation reactions. Four metabolites of C10-DDAC were described for the first time. A detailed assessment of experimental fragmentation spectra allowed to characterize potential oxidation sites. For each annotated metabolite, drift-tube ion-mobility derived collision cross section (DTCCSN2) values were reported, serving as an additional identification parameter and allowing the characterization of changes in DTCCSN2 values following metabolism. Lastly, eight metabolites, including four metabolites of both C12-BAC and C10-DDAC, were confirmed in human urine samples showing high oxidation states through introduction of up to four oxygen atoms. This is the first report of higher oxidized C10-DDAC metabolites in human urine facilitating future biomonitoring studies on QACs.

Gemini cationic surfactant of 1, 3-bis (dodecyl dimethyl ammonium chloride) propane as a novel excellent inhibitor for the corrosion of cold rolled steel in HCl solution

Gemini surfactants have become the research focus of novel excellent inhibitors because of their special structure (two amphiphilic moieties covalently connected at head group by a spacer) and excellent surface properties. It is proved by theoretical calculations that 1, 3-bis (dodecyl dimethyl ammonium chloride) propane (BDDACP) molecules can perform electron transfer with Fe (110). And it has a small fraction free volume, thus greatly reducing the diffusion and migration degree of corrosive particles. The potentiodynamic polarization curve showed that coefficients of cathodic and anodic reaction less than 1 and polarization resistance increased to 1602.9 Ω cm−2 after added BDDACP, confirming that BDDACP significantly inhibited the corrosion reaction by occupying the active site. The electrochemical impedance spectrum of imperfect semi-circle shows that the system resistance increases and double layer capacitance after added BDDACP. Weight loss tests also confirmed that BDDACP forms protective film by occupying the active sites on steel surface, and the maximum inhibition efficiency is 92 %. Comparison of the microscopic morphology showed that steel surface roughness was significantly reduced after added BDDACP. The results of time-of-flight secondary ion mass spectrometry show that steel surface contains some elements from BDDACP, which confirms the adsorption of BDDACP on steel surface.

An in-depth exploration of the impact of novel collector HPDDA on the low-temperature flotation behavior of bastnaesite and quantum chemical calculation

Traditional cationic collectors commonly suffer from drawbacks such as poor solubility and low-temperature resistance, which impede the effectiveness of flotation. Hence, this study designed and synthesised a novel collectors, 2-Hydroxypropane-1,3-bis(dodecyl dimethyl ammonium) bromide (HPDDA), tailored for low-temperature flotation of bastnaesite. The positive charges of the surface molecular electrostatic potential (ESP) of HPDDA concentrate near the two quaternary ammonium groups, with minimal points also appearing between the two N atoms. Near the quaternary ammonium groups, weak van der Waals (vdW) and spatial hindrance occur due to the abundance of polar groups. The Krafft point test reveal that the Krafft point of HPDDA was below 0 °C, significantly higher than that of DDA. HPDDA exhibited excellent pH adaptability and cold resistance, demonstrating outstanding selective capturing capability for bastnaesite even at low temperatures, thereby enabling the separation of bastnaesite from calcite. Analysis through various detection methods such as zeta potential, Fourier transform infrared (FT-IR), contact angle measurement, and X-ray photoelectron spectroscopy (XPS) elucidates the selective adsorption mechanism of HPDDA on the surface of bastnaesite, attributing it to the differences in surface electrification and other properties between bastnaesite and calcite. This work provides new collector and theoretical guidance for solving the low-temperature flotation of bastnaesite.

Innovative multifunctional nanocapsules with antibacterial, perfume, and UV-initiated coating properties

Polymer nanocapsules containing fragrance were fabricated for antibacterial, pleasing scent and UV-coating applications. Poly (2-methacryloyloxy dodecyl dimethyl ammonium chloride-4-allyloxy-2-hydroxybenzophenone)-block-polymethyl methacrylate-iodide (P(QAC12-BP)-b-PMMA-I) was first synthesized by solution iodine transfer polymerization (solution ITP) for use as a polymerizable surfactant in miniemulsion polymerization where benzalkonium chloride (BKC) was used as a cosurfactant. The nanocapsules were prepared using poly(methyl methacrylate–divinylbenzene) (P(MMA–DVB)) as a shell, whereas mangosteen oil (MO) was used as a fragrance core model for aroma. High colloidal stability nanocapsules with a size of about 213 nm were obtained. The nanocapsule surface contained QAC12 segments of 15.10 µmol/g-capsule (UV measurement), giving the high positive charge (+70 mV). An essential oil encapsulated inside the nanocapsule had a high encapsulation efficiency (>90%). The nanocapsules effectively inhibited bacterial growth because of QAC12 and BKC on their surface. The nanocapsules are able to coat the substrate via UV-activated covalent bonds of the BP segment.

Surface engineered long-lasting antibacterial Janus cotton fabrics with excellent moisture/thermal management properties

The hydrophilic property of traditional cotton fabrics invariably facilitates sweat absorption, potentially leading to discomfort such as cold and clammy sensation, and even promoting bacterial proliferation. Herein, we developed a Janus cotton fabric using a surface engineering strategy combining “graft through” and “mist polymerization” methodologies. Through the “graft through” polymerization of methacryloyloxyethyl dodecyl dimethyl ammonium bromide (DMDB), we constructed a well-designed antibacterial coating on the fabric with amphiphilic properties. The resulting polymer, PDMDB, imparts highly efficient and durable antibacterial properties to the cotton fabric, achieving a bcteriostatic rates against S. aureus and E. coli of > 99.9 %. Even after undergoing 150 washing cycles, the residual bactericidal efficacy remains above 99 %. Additionally, the reversible hydrophilic-hydrophobic nature of PDMDB successfully enables the construction of a Janus structure on cotton fabrics via “mist polymerization”. Benefiting from its comprehensive design, the Janus cotton fabrics realize a superior directional liquid transport property. Its water evaporation rate is 1.3–1.5 times higher than that of the original cotton fabric in continuous outdoor moisture management, while maintaining body temperature 5.63 °C lower than that of the surrounding environment. It is worth mentioning that our approach utilizes abundant raw materials and facile modification technologies, thereby providing a favorable guarantee for the mass production and use of Janus cotton fabrics.

Vesicles as a Multifunctional Microenvironment for Electrochemiluminescence Signal Amplification.

Vesicles as a typical interface-rich microenvironment can promote the reaction rate and the intermediate stability, which are promising for introduction in electrochemiluminescence (ECL) signal amplification. In this work, a kind of multilamellar vesicle obtained from sodium bis(2-ethylhexyl) sulfosuccinate (AOT) was used to modify the electrode surface. The AOT vesicle-modified microenvironment could significantly enhance the ECL performances for the luminol/O2 system in a neutral medium. The mechanism study demonstrated that the nanoscale multilamellar vesicles could maintain the vesicle structure on the electrode surface, which substantially improved the electron transfer and reaction rate, luminescence efficiency of the excited-state 3-aminophthalate anion, and stability of the superoxide anion radical. Alternatively, such a multifunctional microenvironment was also able to enhance the ECL signals from the tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)32+)/tripropylamine (TPrA) system. Moreover, another dodecyl dimethyl(3-sulfopropyl) ammonium hydroxide inner salt (DSB)-based vesicle was constructed to further verify the versatility of the vesicle-modified microenvironment for ECL signal amplification. Our work not only provides a versatile microenvironment for improving the efficiency of various ECL systems but also offers new insights for the microenvironment construction using the ordered assemblies in ECL fields.

Boosting laccase activity by synergistic drive of near infrared laser, surfactant, and sodium chloride for healthcare coatings with UV resistance, anti-oxidation, and photothermal conversion

Natural enzymes as green and efficient biocatalysts are essential in constructing multifunctional organic coatings for meeting the green chemistry processes. Herein, the laccase activity was for the first time enhanced by synergistic drive of near infrared (NIR) laser, dodecyldimethyl (3-sulfopropyl) ammonium hydroxide internal salt (SDDAB), and sodium chloride (NaCl). The SDDAB activation on laccase activity is unpredictable, which is advanced compared with conventional predictable ones, including adding mediator and improving reactive temperature. The NaCl can again boost the laccase activity by 29.8 % in the presence of SDDAB. Moreover, NIR laser irradiation again promotes laccase activity by 16.3 % in laccase/SDDAB/NaCl. The total specific activity of laccase exhibits an improvement of 29.2 %, indicating an advancement compared with the activities decrease in immobilized and encapsulated laccases. The Vm of laccase has been improved to 150.9 %. Besides, the hydrogen bonds and van der Waals force between laccase and SDDAB have been verified. Thus, laccase/SDDAB/NaCl was adopted to catalyze the polymerization of gallic acid to create eco-friendly UV-resistant, antioxidative, and photothermal coatings for healthcare. The ultraviolet protection factor (UPF), free radical scavenging ability, and photothermal temperature are 126.28, 95.0 %, and 94.2 °C, respectively. The multifunctional coating not only exhibits the response of sunlight-like photothermal conversion, but also possesses the photothermal response mediated by NIR laser. With the intensity increase of NIR laser irradiation, the surface temperature of modified cotton fabric is gradually strengthened from 29.5 to 43.8 °C. The surface characteristic and chemical composition of the multifunctional coatings were investigated by modern technology. The smartphone was adopted to quickly detect the red, green, and blue (RGB) values for demonstrating the successful fabricating of composite coatings, compared with traditional K/S characterization. Briefly, this work provided a novel, feasible, and elegant idea to boost laccase activity, inspiring more scholars to create advanced organic coatings with natural enzyme as the high-performance green catalysts for meeting green chemistry processes.

Effects of environmental disinfection on microbial population and resistance genes: A case study of the microecology within a panda enclosure

Widespread use of disinfectants raises concerns over their involvement in altering microbial communities and promoting antimicrobial resistance. This study explores the influence of disinfection protocols on microbial populations and resistance genes within an isolated enclosure environment and in the gut of giant pandas (GPs) held within. Samples of panda feces, air conditioning ducts, soil and bamboo were collected before and after disinfection. High-throughput sequencing characterized the microbial flora of GP gut and environmental microbes inside the artificial habitat. Microbial cultures showed that Escherichia coli (34.6%), Enterococcus (15.4%) and other pathogenic bacteria deposited in feces and the enclosure. Isolates exhibit a consistent resistance to disinfectant, with the greatest resistance shown to cyanuric acid, and the lowest to glutaraldehyde-dodecyl dimethyl ammonium bromide (GD-DDAB) and dodecyl dimethyl ammonium bromide (DDAB). The total number of the culturable bacteria in soil and bamboo were significantly diminished after disinfection but increased in the gut. After disinfection, the richness (Chao1 index) of environment samples increased significantly (P < 0.05), while the richness in gut decreased significantly (P < 0.05). Ten genera showed significant change in feces after disinfection. Metagenome sequencing showed that 126 types of virulence genes were present in feces before disinfection and 37 in soil. After disinfection, 110 virulence genes localized in feces and 53 in soil. Eleven virulence genes including ECP and T2SS increased in feces. A total of 182 antibiotic resistance genes (ARGs) subtypes, potentially conferring resistance to 20 classes of drugs, were detected in the soils and feces, with most belonging to efflux pump protein pathways. After disinfection, the number of resistance genes increased both in gut and soil, which suggests disinfection protocols increase the number of resistance pathways. Our study shows that the use of disinfectants helps to shape the microbial community of GPs and their habitat, and increases populations of resistant strain bacteria.

Rapid screening of benzyl dodecyl dimethyl ammonium bromide co-metabolic degrading bacteria based on NIR hyperspectral imaging technology

As a typical disinfectant, the use of benzyl dodecyl dimethyl ammonium bromide (BDAB) has dramatically increased since the emergence of SARS-CoV-2, posing a threat to environmental balance and human health. Screening BDAB co-metabolic degrading bacteria is required for efficient microbial degradation. Conventional methods for screening co-metabolic degrading bacteria are laborious and time-consuming, especially when the number of strains is large. This study aimed to develop a novel method for the rapid screening of BDAB co-metabolic degrading bacteria from the cultured solid medium using near-infrared hyperspectral imaging (NIR-HSI) technology. Based on NIR spectra, the concentration of BDAB in the solid medium can be well predicted by partial least squares regression (PLSR) models, non-destructively and rapidly, with Rc2 > 0.872 and Rcv2 > 0.870. The results show that the predicted BDAB concentrations decrease after degrading bacteria utilization, comparing with the regions where no degrading bacteria grew. The proposed method was applied to directly identify the BDAB co-metabolic degrading bacteria cultured on the solid medium, and two kinds of co-metabolic degrading bacteria RQR-1 and BDAB-1 were correctly identified. This method provides a high-efficiency method for screening BDAB co-metabolic degrading bacteria from a large number of bacteria.

Study on Reversible Solubilization by Adjusting Surfactant Properties.

Solubilization allows us to dissolve hydrophobic materials in water and to carry them to where they are needed. The purpose of this study is to control solubilization, especially the release of solubilized materials, via external stimulation. An amphoteric surfactant, dodecyldimethyl(3-sulfopropyl)ammonium hydroxide inner salt (SB-12), was employed, and a pH change was chosen as the external stimulus. We measured the surface tension of an SB-12 solution via the Wilhelmy method, and the absorbance of a solubilized solution was determined using UV-Vis spectroscopy at various pH values. The surface tension was almost the same at any pH, contrary to our expectations. This result suggests that the adsorption behavior and micelle formation of SB-12 were not affected by pH very much. On the other hand, the solubilization behavior remarkably depended on the pH. In particular, the solubilization ability under the basic condition was much larger than that under the acidic and neutral conditions. Taking advantage of such a difference in solubilization ability under some pH conditions, the solubilized material could be completely removed from the solution. Thus, we clarified the mechanism of release for solubilized materials due to a pH change.

Low concentration quaternary ammonium compounds promoted antibiotic resistance gene transfer via plasmid conjugation

During the pandemic of COVID-19, the amounts of quaternary ammonium compounds (QACs) used to inactivate the virus in public facilities, hospitals and households increased, which raised concerns about the evolution and transmission of antimicrobial resistance (AMR). Although QACs may play an important role in the propagation of antibiotic resistance gene (ARGs), the potential contribution and mechanism remains unclear. Here, the results showed that benzyl dodecyl dimethyl ammonium chloride (DDBAC) and didecyl dimethyl ammonium chloride (DDAC) significantly promoted plasmid RP4-mediated ARGs transfer within and across genera at environmental relevant concentrations (0.0004–0.4 mg/L). Low concentrations of QACs did not contribute to the permeability of the cell plasma membrane, but significantly increased the permeability of the cell outer membrane due to the decrease in content of lipopolysaccharides. QACs altered the composition and content of extracellular polymeric substances (EPS) and were positively correlated with the conjugation frequency. Furthermore, transcriptional expression levels of genes encode for mating pairing formation (trbB), DNA replication and translocation (trfA), and global regulators (korA, korB, trbA) are regulated by QACs. And we demonstrate for the first time that QACs decreased the concentration of extracellular AI-2 signals, which was verified to be involved in regulating conjugative transfer genes (trbB, trfA). Collectively, our findings underscore the risk of increased disinfectant concentrations of QACs on the ARGs transfer and provide new mechanisms of plasmid conjugation.

In Situ Halide Insertion for Efficient and Stable Pure‐Red Perovskite Light‐Emitting Diodes

AbstractSubstantial efforts have been made in boosting the performance of perovskite light‐emitting diodes (PeLEDs). However, there is still a tough challenge to achieve efficient and stable pure‐red PeLEDs with bromide‐iodine mixed quasi‐two‐dimensional (quasi‐2D) perovskite due to the unexpected halide migration under device operation. Here, the strategy of in‐situ halide insertion is proposed by dynamically treating quasi‐2D perovskite film with dodecyl dimethyl ammonium bromide (DDAB), which simultaneously suppresses the vacancy‐induced halide migration, inhibits the nonradiative recombination, and enlarges the perovskite bandgap for stable and efficient pure‐red emission. Meanwhile, a strong Coulombic force between DDAB and the perovskite is formed, which further anchors the halide for the suppression of halide migration. The merits of DDAB‐incorporated perovskites enable over 3‐fold enhancement in PeLED external quantum efficiency (EQE) from 2.25 to 8.16%. Furthermore, highly‐performed bromide‐iodine mixed pure‐red PeLEDs have been reported with a CIE coordinate of (0.707, 0.289), closely approaching the display standard Rec. 2020 (0.708, 0.292). More importantly, good operational and spectral stabilities without any shift of the electroluminescence (EL) spectra during operation have also been observed. Consequently, this work provides a feasible and effective approach for efficient and stable pure‐red PeLEDs.

Biofilm formation by E. coli and S. aureus on cellphone cover: sensitivity to commercially available sanitizers

Presence of pathogens on the cellphones and their accessories poses a significant risk for public health. This study aimed to determine the biofilm-forming capability of S. aureus and E. coli on pieces made from a different commercially available cell phone and aadditionally to test the effectiveness of the most common commercially available sanitizers. Therefore, bacterial biofilm biomasses were quantitatively determined on cellphone covers using crystal violet assay in the presence and absence of common sanitizers. This study revealed that S. aureus and E. coli could form biofilms on the surfaces of all cellphones covers. Additionally, the sanitizers that contain sodium hypochlorite 5.25% and those composed of 38.9% ethanol and 0.05% dodecyl dimethyl ammonium chloride showed the highest log reduction in the number of viable cells after 5 minutes of exposure against biofilms formed by both E. coli and S. aureus compared to other tested sanitizers (chloroxylenol 4.8%, 2-propanol 64%, and ethanol 70%). Moreover, 4.8% chloroxylenol and 70% ethanol-based sanitizers showed log reductions significantly higher than 2-propanol-based ones. In conclusion, cellphone covers were shown to be suitable surfaces for microbial biofilm formation produced by S. aureus and E. coli. The antimicrobial activity of commercially available sanitizers against these bacterial biofilms was variable, with sodium hypochlorite and ethanol/dodecyl dimethyl ammonium chloride sanitizer being the most effective.

Metagenomic insights into the effects of benzyl dodecyl dimethyl ammonium bromide (BDAB) shock on bacteria-driven nitrogen removal in a moving-bed biofilm reactor (MBBR)

The use of disinfectants made from quaternary ammonium compounds (QACs) has greatly increased since the outbreak of SARS-CoV-2. However, the effect of QACs on wastewater treatment performance is still unclear. In this study, a commonly used QAC, i.e., benzyl dodecyl dimethyl ammonium bromide (BDAB), was added to a moving-bed biofilm reactor (MBBR) to investigate BDAB's effect on nutrient removal. When the BDAB concentration was increased to 50 mg L−1, the ammonia removal efficiency (ARE) greatly decreased, as did the nitrate production rate constants (NPR). This inhibition was partly recovered by decreasing the BDAB concentration to 30 mg L−1. Metagenomic sequencing revealed the functional genera present during different stages of the control (Rc) and BDAB-added reactors (Re). The enriched genera (Rudaea, Nitrosospira, Sphingomonas, and Rhodanobacter) in Rc mainly related to the nitrogen metabolism, while the enriched genera in Re was BDAB-concentration dependent. Functional genes analysis suggested that a lack of ammonia oxidase-encoding genes (amoABC) may have caused a decrease in ARE in Re, while the efflux pump-encoding genes emrE, mdfA, and oprM and a gene encoding BAC oxygenase (oxyBAC) were responsible for BDAB resistance. The increase in the total abundance of antibiotic resistance genes (ARGs) in Re revealed a potential risk arising from BDAB. Overall, this study revealed the potential effect and ecological risks of BDAB introduction in WWTPs.

Effect of conventional and Gemini surfactants on the micellar-enhanced ultrafiltration process performance for the separation of Au(III) from aqueous solutions: A dissipative particle dynamics study

Dissipative particle dynamics (DPD) simulation was used to investigate the self-assembled structure of dodecyl trimethyl ammonium bromide (DTAB) and Gemini hexamethylene-1, 6-bis (dodecyl dimethyl ammonium bromide) (12−6−12) surfactants in the aqueous solution. The influence of simulation time and surfactant concentration was studied as the effective parameters on the formation of micelles. The results indicate that by increasing the surfactant concentration, the micellar clusters deform to spherical, wormlike, cylindrical and lamellar shapes, respectively. Subsequently, the effect of surfactant and gold concentrations was investigated for the first time on the performance of the micellar-enhanced ultrafiltration (MEUF) process in the separation of Au(III) from aqueous solutions. The separation efficiency of gold mesomolecules and micellar binding constant was also estimated. The simulation results show the excellent effect of the presence of micelles in the separation of Au(III) using the MEUF process. As the surfactant concentration increases and the micelles grow in size, the probability of bonding between the metal mesomolecules and the micelles also increases and the passage of the gold beads through the polymeric membrane decreases.

Innovative bifunctional heat storage nanocapsules containing polymerizable surfactant for antimicrobial thermoregulating clothes

Bifunctional poly(methyl methacrylate)/Rubitherms®27 (PMMA/RT27) nanocapsules were fabricated by miniemulsion polymerization using poly(2-methacryloyloxy dodecyl dimethyl ammonium chloride-4-allyloxy-2-hydroxy benzophenone)-block-polymethyl methacrylate-iodide (P(QAC12-BP)-b-PMMA-I) as a polymerizable surfactant. Approximately 50-nm spherical core-shell nanocapsules were formed with a highly positive surface charge (≥ +70 mV) derived from the quaternary ammonium (QA) groups in QAC12 units. The QA groups distributed on the nanocapsules’ surfaces effectively presented cationic characteristics and antimicrobial performance. High RT27 loading and encapsulation efficiency PMMA nanocapsules were produced using an MMA: RT27 ratio of 50: 50 with high latent heats of the encapsulated RT27, close to those of the pristine ones. Because of the existence of the BP unit in the polymerizable surfactant located on nanocapsules’ surfaces, the obtained nanocapsules were strongly coated on cotton fabrics by irradiation with UV light, giving them greater washing durability than using an external binder. The coated fabrics exhibited effective antimicrobial performance against S. epidermidis and C. glutamigum. Therefore, the fabricated PMMA/RT27 nanocapsules presenting thermoregulating and antimicrobial properties are well suited for application on textiles.

Improvement of Antibacterial and Antifouling Properties of a Cellulose Acetate Membrane by Surface Grafting Quaternary Ammonium Salt.

Through etherification reaction, epoxy propyl dimethyl dodecyl ammonium chloride (EPDMDAC) was grafted onto the surface of a cellulose acetate (CA) membrane to prepare a stable nonleaching antibacterial antifouling membrane (QCA-X). The results showed that with the extension of grafting reaction time, the quaternary ammonium salt groups on the membrane surface increased and the hydrophilicity was enhanced. Compared with those of the CA membrane, the filtration capacity and antifouling performance of the QCA-X membrane are improved. When the grafting time is 4 h, the water permeability and flux recovery rate of the QCA-4 membrane are increased by 139 and 21.5%, respectively. The QCA-X membrane showed excellent antibacterial performance, and the sterilization rate against S. aureus and E. coli was more than 99.99%. After four repeated antibacterial cycles, the bactericidal rates against S. aureus and E. coli were maintained at about 99.69 ± 0.02 and 99.98 ± 0.02%, respectively, with good antibacterial persistence. Moreover, the QCA-X membrane can effectively inhibit bacterial adhesion. Mild and simple EPDMDAC grafting modifications improve the antibacterial, antifouling, and antibioadhesion properties of the CA membrane, showing its application potential in long-term water treatment, especially in biofouling water treatment.

Adsorption behaviors and emission properties of p-sulfonatocalixarene/ammonium-based surfactant systems: A comparison between the effects of gemini surfactant and its corresponding monomeric surfactant

So far, the research on calixarene/surfactant systems has been mainly focused on their aggregation characteristics due to their potential applications as stimuli-responsive systems, while the reports about their absorption behavior and spectroscopic properties have been limited. Understanding basic properties of supra-amphiphilic molecules is of great significance to improve their application performance and expand their application potential. In the present study, the interactions of p-sulfonatocalix[n]arenes (SC[n], n = 4, 6 and 8) with the cationic surfactants (including dodecyltrimethyl ammonium bromide (DTAB), pentamethylene-1,5-bis (dimethyldodecyl ammonium bromide) (12-5-12), and octamethylene-1,8-bis(dimethyldodecyl ammonium bromide (12-8-12)) were studied by measuring surface tension, fluorescence spectra and 1H NMR spectra. It was found that SC[n] changed the absorption behaviors of 12-s-12 (s = 5 and 8) and DTAB at air/water surface in different ways. In the presence of SC[n], the value of γ for 12-s-12 remains almost constant until 12-s-12 content reaches C1, then decreases sharply until C2, followed by a slow decrease up to the CMC. The surface tension of DTAB/SC[n] solution begins to decrease at a very low concentration of DTAB until Ca, followed by a short plateau until Cb, and then, the surface tension increases sharply until Cc, after which, the surface tension curve gradually overlaps with that of single DTAB solution. Meanwhile, the binding of SC[n] with these surfactants makes SC[n] emit fluorescence, and the quantum yields for SC[n]/12-s-12 systems are higher than those for SC[n]/DTAB systems. Supra-amphiphiles have been expected as smart materials. This study may provide meaningful information for application of calixarene-based supra-amphiphiles.

Removal of Cr(VI) in aqueous solution using cationic gemini surfactant-modified rectorite

The adsorption of hexavalent chromium (Cr(VI)) on rectorite (REC) modified by gemini surfactant (butane-1,4-bis (dodecyl dimethyl ammonium bromide)) (gBDDA) was investigated in this research. The results of a series of characterization methods such as X-ray diffraction (XRD), infrared spectroscopy, and thermogravimetric analysis proved that gBDDA was successfully embedded into the interlayer of REC. The effect of the amount of gBDDA on the adsorption of Cr(VI) by gBDDA-modified REC was studied (gBDDA: cation exchange capacity = 1:2 or 1:4). The adsorption capacity of Cr(VI) by gemini surfactant-modified REC reached 38 mg/g, which was higher than that of tetradecyl trimethyl ammonium bromide-modified REC. In addition, ultrasound-assisted synthesis was found to have an effect on the adsorption capacity of REC modified with a high ratio of gemini surfactant. The structures of gBDDA before and after adsorption were analyzed to clarify the adsorption mechanism. The electrostatic interaction between Cr(VI) and two positively charged groups in the gBDDA was found to be crucial during the adsorption process. The foundings of this study demonstrate that REC modified by gBDDA can be used as an adsorbent for the removal of Cr(VI) in water.